Chemokines are a family of molecules having a high degree of homology at the amino acid level. IL8 and MCAF have been extensively studied and found to have proinflammatory properties, however the biological properties of several other members are either unknown or ill defined. We investigated the biological properties of IP-10, MIP-1alpha,beta and RANTES, the binding characteristics of MCAF, MIP-1alpha,beta and RANTES receptors, and the role phosphorylation plays in chemokine ligand induced desensitization. We found IP-10, MIP-1alpha,beta and RANTES to be chemotactic for T-cells, and monocytes. MIP-1alpha has apparent selectivity in chemoattracting anti-CD3 activated CD8+ T-cells. MIP- 1beta has apparent selectivity in chemoattracting anti-CD3-activated CD4+ T-cells. MIP-1alpha,beta have similar selectivity in inducing CD4+ and CD8+ cells to adhere to IL1 stimulated endothelial cells. Receptor binding studies have identified specific receptors for MCAF, MIP- 1alpha,beta and RANTES on monocytes. These receptors appear to bind multiple chemokines. Chemokine responses can be desensitized by pretreatment with a high concentration of chemokine. We have shown that treatment with IL8 leads to the specific phosphorylation of an 55 kd protein and pretreatment of cells with staurosporine, a protein kinase C inhibitor, will partially abrogate the desensitizing effect of high concentrations of IL8. We are now creating IL8 receptor mutants to examine the role of serine and threonine phosphorylation plays in receptor desensitization.